Project Summary Heart disease was responsible for 614,348 deaths in 2014, making it the leading cause of death for both women and men in the United States [1]. Over 400,000 coronary artery bypass graft (CABG) procedures were performed in 2010 alone, with reintervention rates reported to be as high as 8.8% [2]. In addition to limited autologous tissue availability, the treatment of small diameter vascular disease is hindered by the compliance mismatch of currently delivered grafts that lead to subsequent failure via intimal hyperplasia (IH) and graft thrombosis [3-7]. Despite significant recent progress, the development of a compliance matched and biologically functional TEVG has remained elusive. The utility of biopolymer based constructs have been promising [8], however there has been limited success in modulating the compliance and mechanical properties of these materials. Our overall hypothesis is that a TEVG composed primarily of alternating layers of gelatin and tropoelastin can be compliance matched to native tissue and, when lined with an autologous blood derived endothelium, reduce the current failure modes of small diameter vascular grafts. We further hypothesize that the elution of TGF?2 from our graft will maintain the compliance of our TEVG following implantation. Therefore, the goal of this proposal is to assess the matrix remodeling, mechanical properties, thrombosis, and IH of our endothelialized, biomimetic, and compliance matched TEVG using both an in-vitro and in-vivo approach. This goal will be met by completing the following specific aims. Specific Aim 1: Fabricate a layered TEVG that is compliance matched to a rat aorta and an ovine carotid artery using our established experimental/computational optimization approach. Specific Aim 2: Determine the compliance, load dependent ECM organization, and protease activity of our cell seeded TEVGs as TGF?2 is released during mechanically stimulated bioreactor culture. Specific Aim 3: Determine the compliance (in-vivo), patency, thrombogenicity, IH, and ex-vivo load dependent microstructure and mechanical properties of TGF?2 eluting and compliance matched TEVGs. Specific Aim 4: Assess the patency, thrombogenicity, IH, and ex-vivo load dependent microstructure and mechanical properties of TGF?2 eluting and compliance matched TEVGs lined with ECs derived from autologous adult versus autologous umbilical cord blood following ovine carotid implantation. Successful completion of the proposed aims will result in a TEVG that immunocompatible, antithrombogenic, and maintains it's compliance matched mechanical properties following implantation. The proposed research will also generate novel information regarding the extracellular matrix remodeling of biopolymer based vascular grafts as they remodeled both in-vitro and in-vivo.